Dehydrogenation with a nonacidic multimetallic catalyst

ABSTRACT

Dehydrogenatable hydrocarbons are dehydrogenated by contacting them at dehydrogenation conditions with a nonacidic catalytic composite comprising a combination of catalytically effective amounts of a platinum or palladium component, an iridium component, a Group IVA metallic component and an alkali or alkaline earth component with a porous carrier material. A specific example of the nonacidic, multimetallic catalytic composite disclosed herein is a combination of a platinum component, an iridium component, a germanium component and an alkali or alkaline earth component with an alumina carrier material. The amounts of the catalytically active components contained in this last composite are, on an elemental basis, 0.01 to 2 wt. % platinum, 0.01 to 2 wt. % iridium, 0.01 to 5 wt. % germanium and 0.1 to 5 wt. % of the alkali or alkaline earth metal.

llttiteel tats t t t Hayes DEHYDIRDGENATION WITH A NONACllDlCMULTTMETALLTC CATALYST [75] Inventor: John C. Hayes, Palatine, Ill.

[73] Assignee: Universal Dil Products @ompany, Des Plaines, Ill.

[22] Filed: June ll, 1973 [21] Appl. No.: 365,877

Related US. Application Data [63] Continuation-in-part of Ser. No.27,457, April 10,

i970, abandoned.

[56] References Cited UNITED STATES PATENTS 10/1972 Juquin et a1.262/466 PT 2/1973 Buss et al 208/139 [111 Adam Dec. 24, WW

Primary Examiner-C. Davis Attorney, Agent, or Firm-James R. Hoatson, Jr.; Thomas K. McBride; William H. Page, II

[57] ABSTRACT Dehydrogenatable hydrocarbons are dehydrogenated bycontacting them at dehydrogenation conditions with a nonacidic catalyticcomposite comprising a combination of catalytically effective amounts ofa platinum or palladium component, an iridium component, a Group IVAmetallic component and an alkali or alkaline earth component with aporous carrier material. A specific example of the nonacidic,multimetallic catalytic composite disclosed herein is a combination of aplatinum component, an iridium component, a germanium component and analkali or alkaline earth component with an alumina carrier material. Theamounts of the catalytically active components contained in this lastcomposite are, on an elemental basis, 0.01 to 2 wt. platinum, 0.01 to 2wt iridium, 0.01 to 5 wt. germanium and 0.1 to 5 wt. of the alkali'oralkaline earth metal.

116 Claims, N0 Drawings DEI-IYDROGENATION WITH A NONACIDICMULTIMIETALLIIC CATALYST CROSS-REFERENCES TO RELATED APPLICATIONS Thisapplication is a continuation-in-part of my prior, copending applicationSer. No. 27,457, filed Apr. 10, 1970, now abandoned all of the teachingsof which are specifically incorporated herein by reference.

The subject of the present invention is, broadly an improved method fordehydrogenating a dehydrogenatable hydrocarbon to produce a producthydrocarbon containing the same number of carbon atoms but fewerhydrogen atoms. In a narrower aspect, the present invention is a methodof dehydrogenating normal paraffin hydrocarbons containing 4 to 30carbon atoms per molecule to the corresponding normal mono-olefins withminimum production of side products. Another aspect of the presentinvention involves a novel nonacidic, multimetallic catalytic compositeconprising a combination of catalytically effective amounts of aplatinum or palladium component, an iridium component, a Group IVAmetallic component, and an alkali or alkaline earth metal component witha porous carrier material. This composite has highly preferredcharacteristics of activity, selectivity, and stability when it isemployed in the dehydrogenation of dehydrogenatable hydrocarbons such asaliphatic hydrocarbons, napheth'enic hydrocarbons and alkylaromatichydrocarbons.

The dehydrogenation of dehydrogenatable hydrocarbons is an importantcommercial process because of the great and expanding demand fordehydrogenated hydrocarbons for use in the manufacture of variouschemical products such as detergents, plastics, syn.-

the'tic rubbers, pharmaceutical products, high octane gasoline,perfumes, drying oils, ion-exchange resins, and various other productswell known to those skilled in the art. One example of this demand is inthe manufacture of high octane gasoline by using C and C mono-olefins toalkylate isobutane. A second example is the greatly increasedrequirements of the petrochemic'al industry for the production ofaromatic hydrocarbons from the naphthene component of petroleum. Anotherexample of this demand is in the area of dehydrogenation of. normalparaffin hydrocarbonsto produce normal mono-olefins having 4 to 30carbon atoms per molecule. These normal mono-olefins can, in turn, be

. utilized in the synthesis of vast numbers of other chemidetergentindustry where they are utilized to alkylate an alkylatable aromaticsuch as benzene, with subsequent transformation of the productarylalkane into a wide variety of biodegradable detergents such as the.alkylaryl sulfonate type of detergent which is most widely used todayfor house-hold, industrial, and commercial purposes. Still another largeclass of detergents produced from these normal mono-olefins are theoxyalkylated phenol derivatives in which the alkyl phenol base isprepared by the alkylation of phenol with these normal mono-olefins. Yetanother type of detergent produced from these normal mono-olefins is abiodegradable alkylsulfate formed by the direct sulfation of the normalmono-olefin. Likewise, the olefin can be subjected to direct sulfonation to make biodegradable alkenylsulfonates. As a furtherexample, these monoolefins can be hydrated to produce alcohols whichthen, in turn can be used to produce plasticizers, synthetic lube oilsand the like products.

Regarding the use of products made by the dehydrogenation ofalkylaromatic hydrocarbons, these find wide application in industriesincluding the petroleum, petrochemical, pharmaceutical, detergent,plastic industries, and the like. For example, ethylbenzene isdehydrogenated to produce styrene which is utilized in the manufacturingor polystyrene plastics, styrenebutadiene rubber, and the like products.Isopropylbenzene is dehydrogenated to form alphamethyl styrene which, inturn, is extensively used in polymer formation and in the manufacture ofdrying oils, ion-exchange resins and the like material.

Responsive to this demand for these dehydrogenation products, the arthad developed a number of alternative methods to produce them incommercial quantities. One method that is widely utilized involves theselective dehydrogenation of dehydrogenatable hydrocarbons by contactingthe hydrocarbons with a suitable catalyst at dehydrogenation conditions.As is the case with most catalytic procedures, the principal measure ofeffectiveness for this dehydrogenation method involves the ability toperform its intended function with minimum interference of sidereactions for extended periods of time. The analytical terms used in theart to broadly measure how well a particular catalyst performs itsintended functions in a particular hydrocarbon conversion reaction areactivity, selectivity, and stability, and for purposes of discussionhere these terms are generally defined for a given reactant as follows:(1) activity is a measure of the catalysts ability to convert thehydrocarbon reactant into products at a specified severity level whereseverity level means the conditions used that is, the temperature,pressure, contact time, and presence of diluents such as H (2)selectivity usually refers to the amount of desired product or productsobtained relative to theamount of the reactant charged or converted; (3)stability refers to the rate of change with time of the activity andselectivity parameters obviously the smaller rate implying the morestable catalyst. More specifically, in a dehydrogenation process,activity commonly refers to the amount of conversion that takes placefor a given dehy drogenatable hydrocarbon at a specified severityleveland is typically measured on the basis of disappearance of thedehydrogenatable hydrocarbon; selectivity is typically measured by theamount, calculated on a mole percent of converted dehydrogenatablehydrocarbon basis, of the desired dehydrogenated hydrocarbon obtained atthe particular activity or severity level; and stability istypicallyequated to the rate of change with time of activity as measuredby disappearance of the dehydrogenatable hydrocarbon and of selectivityas measured by the amount of desired hydrocarbon produced. Accordingly,the major problem facing workers in the hydrocarbon dehydrogenation artis the development ofa more active and selective catalytic compositethat has good stability characteristics.

I have now found a multimetallic catalytic composite which possessesimproved activity, selectivity, and stability when it is employed in aprocess for the dehydrogenation of dehydrogenatable hydrocarbons. Inparticular, I have determined that a superior dehydrogenation catalystcomprises a nonacidic combination of catalytically effective amounts ofa platinum or palladium component, an iridium component, a Group IVAmetallic component, and an alkali or alkaline earth component with aporous carrier material in a manner such that the components areuniformly dispersed throughout the porous carrier material, the platinumor palladium and iridium components are reduced to the correspondingelemental state annd the Group IVA metal and the alkali or alkalineearth metals are present in a positive oxidation state. This catalystcan, in turn, enable the performance of a dehydrogenation process to besubstantially improved. Moreover, particularly good results are obtainedwhen this multimetallic catalyst is utilized in the dehydrogenationoflong chain normal paraffins to produce the corresponding normalmono-olefins with minimization of side reactions such as skeletalisomerization, aromatization and cracking. In sum, the current inventioninvolves the significant finding that a combination of an iridiumcomponent and a Group IVA metallic component can be utilized tobenefically interact with a platinum-containing dehydrogenation catalystif the metal moieties are uniformly dispersed in the catalyst and iftheir oxidation states are controlled as hereinafter specified.

It is, accordingly, one object of the present invention to provide anovel method for dehydrogenation of dehydrogenatable hydrocarbonsutilizing a multimetallic nonacidic catalytic composite containing aplatinum or palladium component, an iridium component, a Group IVAmetallic component, and an alkali or alkaline earth component combinedwith a porous carrier material. A second object is to provide a novelnonacidic catalytic composite having superior performancecharacteristics when utilized in a dehydrogenation process. Anotherobject is to provide an improved method for the dehydrogenation ofnormal paraffin hydrocarbons to produce normal mono-olefins. Yet anotherobject is to improve the performance of a nonacidic platinum-containingdehydrogenation catalyst by using a combination of components, iridiumand a Group IVA metal, to beneficially interact and promote the platinummetal.

In brief summary, one embodiment of the present invention involves anonacidic catalytic composite comprising a porous carrier materialcontaining, on an elemental basis, about 0.01 to about 2 wt.% platinumor palladium, about 0.01 to about 2 wt.% iridium, about 0.01 to about 5wt.% Group IVA metal and about 0.1 to about 5 wt.%- of an alkali oralkaline earth metal, wherein the platinum or palladium, Group IVAmetal, iridium and alkali or alkaline earth metal components areuniformly dispersed throughout the porous carrier material, whereinsubstantially all of the platinum or palladium and iridium componentsare present in the corresponding elemental metallic state, whereinsubstantially all of the Group IVA metal component is present in anoxidation state above that of the elemental metal and whereinsubstantially all of the alkali or alkaline earth metal component ispresent in an oxidation state above that of the elemental metal.

A second more specific embodiment relates to a nonacidic catalyticcomposite comprising an alumina carrier material containing, on anelemental basis, about 0.05 to about 1 wt. platinum or palladium, about0.05 to about I wt. iridium, about 0.05 to about 2 wt. Group IVA metaland about 0.25 to about 3.5 wt. alkali or alkaline earth metal, whereinthe platinum or palladium, Group IVA metal, iridium and alkali oralkaline earth metal components are uniformly dispersed throughout thealumina carrier material, wherein substantially all of the platinum orpalladium and iridium components are present in the correspondingelemental metallic state, wherein substantially all ofthe Group IVAmetal component is present in an oxidation state above that of theelemental metal and wherein substantially all ofthe alkali or alkalineearth metal component is present in an oxidation state above that of theelemental metal.

A third embodiment comprehends a method for dehydrogenating adehydrogenatable hydrocarbon which essentially involves contacting thedehydrogenatable hydrocarbon at dehydrogenation conditions with themultimetallic catalytic composite defined in the first embodiment.

Another embodiment involves a method for the selective dehydrogenationof a normal paraffin hydrocarbon containing about 4 to 30 carbon atomsper molecule to the corresponding normal mono-olefins. The methodessentially involving contacting the normal paraffin hydrocarbons andhydrogen at dehydrogenation conditions with a catalytic composite of thetype defined in the first embodiment.

Other objects and embodiments of the present invention include specificdetails regarding essential and preferred ingredients of the disclosedmultimetallic catalytic composite, preferred amounts of ingredients for.this composite, suitable methods of composite preparation,dehydrogenatable hydrocarbons that are preferably used with thiscatalyst in a dehydrogenation process, operating conditions that can beutilized with this catalyst in a dehydrogenation process and the likeparticulars. These objects and embodiments are disclosed in thefollowing detailed explanation of the various technical aspects of thepresent invention. It is to be noted that: (l) the terms catalyst andcatalytic composite are used herein in an equivalent and interchangeablemanner; (2) the expression uniformly dispersed throughout a carriermaterial is intended to mean that the concentration of the component isapproximately the same in any reasonably divisible portion of thecarrier material; and, (3) the term nonacidic" means that the catalystproduces less than 10% conversion of l-butene to isobutylene when testedat dehydrogenation conditions, and preferably less than 1%.

Regarding the dehydrogenatable hydrocarbon that is subjected to theinstant method, it can, in general, be an organic compound having 2 to30 carbon atoms per molecule and containing at least 1 pair of adjacentcarbon atoms having hydrogen attached thereto. That is, it is intendedto include within the scope of the present invention the dehydrogenationof any organic compound capable of being dehydrogenated to produceproducts containing the same number of carbon atoms but fewer hydrogenatoms, and capable of being vaporized at the dehydrogenation conditionsused herein. More particularly, suitable dehydrogenatable hydrocarbonsare: aliphatic compounds containing 2 to 30 carbon atoms per molecule,alkylaromatic hydrocarbons where the alkyl group contains 2 to 6 carbonatoms, and naphthenes or alkyl-substituted naphthenes. Specific examplesof suitable dehydrogenatable hydrocarbons are: I alkanes such as ethane,propane, n-butane, isobutanes, n-pentane, isopentane, n-hexane,2-methylpentane, 2,2-dimethylbutane, n-heptane, n-

octane, 2-methylhexane, 2,2,3-trimethylbutane, and the like compounds;(2) naphthenes such as cyclopentane, methylcyclopentane,ethylcyclopentane, n-propylcyclopentane, cyclohexane,isopropylcyclopentane, 1,3-dimethylcyclohexane, and the like compounds;and (3) alkylaromatics such as ethylbenzene, n-propylbenzene,n-butylbenzene, l,3 ,5- triethylbenzene, isopropylbenzene,isobutylbenzene, ethylnaphthalene, and the like compounds.

In a preferred embodiment, the dehydrogenatable hydrocarbon is a normalparaffin hydrocarbon having about 4 to about 30 carbon atoms permolecule. For example, normal paraffin hydrocarbons containing about to18 carbon atoms per molecule are dehydrogenated by the subject method toproduce the corresponding normal mono-olefm which can, in turn, bealkylated with benzene and sulfonated to make alkylbenzene sulfonatedetergents having superior biodegradability. Likewise, n-alkanes having10 to l8 carbon atoms per molecule can be dehydrogenated to thecorresponding normal mono-olefin which, in turn, can be sulfated orsulfonated to make excellent detergents. Similarly, n-alkanes having 6to 10 carbon atoms per molecule can be dehydrogenated to form thecorresponding mono-olefins which can, in turn, be hydrated to producevaluable alcohols. Preferred feed streams for the manufacture ofdetergent intermediates contain a mixture of 4 or 5 adjacent normalparaffin homologues such as C to C C to C14, C to C and the likemixtures.

An essential feature of the present invention involves the use ofanonacidic, multimetallic catalytic composite comprising a combinationof catalytically effective amounts of a platinum or palladium component,an iridium component, a Group IVA metallic component, and an alkali oralkaline earth component with a porous carrier material.

Considering first the porous carrier material, it is preferred that thematerial be a porous, adsorptive, high surface area support having asurface area of about 25 to about 500 m /g. The porous carrier materialshould be relatively refractory to the conditions utilized in thedehydrogenation process and it is intended to include within the scopeof the present invention carrier materials which have traditionally beenutilized in hydrocarbon conversion catalysts such as: (l) activatedcarbon, coke, or charcoal; (2) silica or silica gel, silicon carbide,clays, and silicates including those synthetically prepared andnaturally occurring, which may or may not be acid treated for example,attapulgus clay, china clay, diatomaceous earth, fullers earth, kaolin,kieselguhr, etc., (3) ceramics, porcelain, crushed firebrick, bauxite,(4) refractory inorganic oxides. such as alumina, titanium dioxide,zirconium dioxide, chromium oxide, zinc oxide, magnesia, thoria, boria,silicaalumina, silica-magnesia, chromia-alumina, aluminaboria,silica-zirconia, etc.; (5) crystalline aluminosilicates such asnaturally occurring or synthetically prepared mordenite and/0rfaujasite, either in the hydrogen form or in a form which has beentreated with multivalent cations; and, (6) combination of elements fromone or more of'these groups. The preferred porous carrier materials foruse in the present invention are refractory inorganic oxides, with bestresults obtained with an alumina carrier material. Suitable aluminamaterials are the crystalline aluminas known as the gamma-, e ta, andthetaaluminas, with gamma-alumina giving best results. In addition, insome embodiments, the alumina carrier material may contain minorproportions of other well known refractory inorganic oxides such assilica, zirconia, magnesia, etc.; however, the preferred support issubstantially pure gammaalumina. Preferred carrier materials have anapparent bulk density of about 0.3 to about 0.7 g/cc and surface areacharacteristics such that the average pore diameter is about 20 to 300Angstroms, the pore volume is about 0.1 to about l cc/g and the surfacearea is about 1-00 to about 500 m /g. In general, excellent results aretypically obtained with a gamma-alumina carrier mate rial which is usedin the form of spherical particles having: a relatively small diameter(i.e., typically about 1/16 inch), an apparent bulk density of about 0.5g/cc, a pore volume of about 0.4 cc/g and a surface area of about m /g.

The preferred alumina carrier material may be prepared in any suitablemanner and may be synthetically prepared or natural occurring. Whatevertype of alumina is employed it may be activated prior to use by one ormore treatments including drying, calcination, steaming, etc., and itmay be in a form known as activated alumina, activated alumina ofcommerce, porous alumina, alumina gel, etc. For example, the aluminacarrier may be prepared by adding a suitable alkaline reagent, such asammonium hydroxide to a salt of aluminum such as aluminum chloride,aluminum nitrate, etc., in an amountto form an aluminum hydroxide gelwhich upon drying and calcining is converted to alumina. The aluminacarrier may be formed in any desired shape such as spheres, pills,cakes, extrudates, powders, granules, etc., and utilized in any desiredsize. For the purpose of the present invention a particularly preferredform of alumina is the sphere; and alumina spheres may be continuouslymanufactured by the wellknown oil drop method which comprises; formingan alumina hydrosol by any of the techniques taught in the art andpreferably by reacting aluminum metal with hydrochloric acid; combiningthe resulting hydrosol with a suitable gelling agent; and dropping theresultant mixture into an oil bath maintained at elevated temperatures.The droplets'of the mixture remain in the oil bath until they set andform hydrogel spheres. The spheres are then continuously withdrawn fromthe oil bath and typically subjected to specific aging treatments in oiland an ammoniacal solution to further improve their physicalcharacteristics. The resulting aged and gelled particles are then washedand dried at a relatively low temperature of about 300F. to about 400F.and subjected to a calcination procedure at a temperature of about 850F.to about 1300F. for a period of about 1 to 20 hours. It is a goodpractice to subject the calcined particles to a high temperaturetreatment with steam in order to remove undesired acidic components suchas any residual chloride. This method effects conversion of the aluminahydrogel to the corresponding crystalline gamma-alumina. See theteachings of US. Pat. No. 2,620,3l4 for additional details.

One essential constituent of the instant multimetallic catalyticcomposite is the Group IVA metallic component. By the use of the genericterm Group IVA metallic component it is intended to cover the metals ofGroup IVA of the Periodic Table. More specifically, it is intended tocover: germanium, tin, lead and mixtures of these metals. It is anessential feature of the present invention that substantially all of theGroup IVA metallie component is present in the final catalyst in anoxidation state above that of the elemental metal. In other words, thiscomponent may be present in chemical combination with one or more of theother ingredients of the composite, or as a chemical compound of theGroup IVA metal such as the oxide, sulfide, halide, oxyhalide,oxychloride, aluminate, and the like compounds. Based on the evidencecurrently available, it is believed that best results are obtained whensubstantially all of the Group IVA metallic component exists in thefinal composite in theform of the corresponding oxide such as the tinoxide, germanium oxide, and lead oxide, and the subsequently describedoxidation and reduction steps, that are preferably used in thepreparation of the instant composite, are believed to result in acatalytic composite which contains an oxide of the Group IVA metalliccomponent. Regardless of the state in which this component exists in thecomposite, it can be utilized therein in any amount which iscatalytically effective, with the preferred amount being about 0.01 toabout wt. thereof, calculated on an elemental basis and the mostpreferred amount being about 0.05 to about 2 wt. The exact amountselected within this broad range is preferably determined as a functionof the particular Group IVA metal that is utilized. For instance, in thecase where this component is lead, it is preferred to select the amountof this component from the low end of this range namely, about 0.01 toabout l wt. Additionally, it is preferred to select the amount of leadas a function of the amount of the platinum group component as explainedhereinafter. In the case where this component is tin, it is preferred toselect from a relatively broader range ofabout 0.05 to about 2 wt.thereof. And, in the preferred case, where this component is germanium,the selection can be made from the full breadth of the stated rangespecifically, about 0.01 lto about 5 wt. with best results at about 0.05to about 2 wt.

This Group IVA component may be incorporated in the composite in anysuitable manner known to the art to result in a uniform dispersion ofthe Group IVA moiety throughout the carrier material such ascoprecipitation or cogellation with the porous carrier material, ionexchange with the carrier material, or impregnation of the carriermaterial at any stage in its preparation. It is to be noted that it isintended to include within the scope of the present invention allconventional procedures for incorporating a metallic component in acatalytic composite, and the particular method of incorporation used isnot deemed to be an essential feature of the present invention so longas the Group IVA component is uniformly distributed throughout theporous carrier material. One acceptable method of incorporating theGroup IVA component into the catalytic composite involves cogelling theGroup IVA component during the preparation of the preferred carriermaterial, alumina. This method typically involves the addition of asuitable soluble compound of the Group IVA metal of interest to thealumina hydrosol. The resulting mixture is then commingled with asuitable gelling agent, such as a relatively weak alkaline reagent, andthe resulting mixture is thereafter preferably gelled by dropping into ahot oil bath as explained hereinbefore. After aging, drying andcalcining the resulting particles there is obtained an intimatecombustion of the oxide of the Group IVA metal and alumina. Onepreferred metnod incorporating this component into the compositeinvolves utilization of a soluble decomposable compound of theparticular Group IVA metal of interest to impregnate the porous carriermaterial either before, during or after the carrier material iscalcined. In general, the solvent used during this impregnation step isselected on the basis of its capability to dissolve the desired GroupIVA compound without affecting the porous carrier material which is tobe impregnated; ordinarily, good results are obtained when water is thesolvent; thus the preferred Group IVA compounds for use in thisimpregnation step are typically water-soluble and decomposable. Examplesof suitable Group IVA compounds are: germanium difluoride, germaniumtetraalkoxide, germanium dioxide, germanium tetrafluoride, germaniummonosulfide, tin chloride, tin bromide, tin dibromide di-iodide, tindichloride diiodide, tin chromate, tin difluoride, tin tetrafluoride,tin tetraiodide, tin sulfate, tin tartrate, lead acetate, lead bromate,lead bromide, lead chlorate, lead chloride, lead citrate, lead formate,lead lactate, lead malate, lead nitrate, lead nitrite, lead dithionate,and the like compounds. In the case where the Group IVA component isgernamium, a preferred impregnation solution is germanium tetrachloridedissolved in anhydrous alcohol. In the case of tin, tin chloridedissolved in water is preferred. In the case of lead, lead nitratedissolved in water is preferred. Regardless of which impregnationsolution is utilized, the Group IVA component can be impregnated eitherprior to, simultaneously with, or after the other metallic componentsare added to the carrier material. Ordinarily, best results are obtainedwhen this component is impregnated simultaneously with the othermetallic components of the composite. Likewise, best results areordinarily obtained when the Group IVA component is germanium oxide ortin oxide.

Regardless of which Group IVA compound is used in thepreferredimpregnation step, it is essential that the Group IVA metalliccomponent be uniformly distributed throughout the carrier material. Inorder to achieve this objective when this component is incorporated byimpregnation, it is necessary to maintain the pH of the impregnationsolution at a relatively low level corresponding to about 7 to about 1or less and to dilute the impregnation solution to a volume which is atleast approximately the same or greater than the volume of the carriermaterial which is impregnated. It is preferred to use a volume ratio ofimpregnation solution to carrier material of at least 121 and preferablyabout 2:1 to about 10:1 or more. Similarly, it is preferred to use arelatively long contact time during the impregnation step ranging fromabout one-fourth hour up to about one-half hour or more before drying toremove excess solvent in order to insure a high dispersion of the GroupIVA metallic component on the carrier material. The carrier material is,likewise preferably constantly agitated during this preferredimpregnation step.

A second essential ingredient of the subject catalyst is the platinum orpalladium component. That is, it is intended to cover the use ofplatinum or palladium or mixtures thereof as a second component of thepresent composite. It is an essential feature of the present inventionthat substantially all of this platinum or palladium component existswithin the final catalytic composite in the elemental metallic state.Generally, the amount of this component present in the final catalystcomposite is small compared to the quantities of the other componentscombined therewith. In fact, the platinum or palladium componentgenerally will comprise about 0.01 to about 2 wt. of the final catalyticcomposite, calculated on an elemental basis. Excellent results areobtained when the catalyst contains about 0.05 lto about 1 wt. ofplatinum or palladium metal.

This platinum or palladium component may be incorporated in thecatalytic composite in any suitable manner known to result in arelatively uniform distribution of this component in the carriermaterial such as coprecipitation or cogellation, ion-exchange, orimpregnation. the preferred method of preparing the catalyst involvesthe utilization of a soluble, decomposable compound of platinum, orpalladium to impregnate the carrier material in a relatively uniformmanner. For example, this component may be added to the support bycommingling the latter with an aqueous solution of I chloroplatinic orchloropalladic acid. Other watersoluble compounds of platinum orpalladium may be employed in impregnation solutions and include ammoniumchloroplatinate, bromoplatinic acid, platinum dichloride, platinumtetrachloride hydrate, platinum dichlorocarbonyl dichloride,dinitrodiamino-platinum, palladium chloride, palladium nitrate,palladium sulfate, etc. The utilization of a platinum or palladiumchloride compound, such as chloroplatinic or chloropalladic acid, isordinarily preferred. Nitric acid or hydrogen chloride or the like acidis also generally added to the impregnation solution in order to furtherfacilitate the uniform distribution of the metallic component throughoutthe carrier material. In addition, it is generally preferred toimpregnate the carrier material after it has been calcined in order tominimize the risk of washing away the valuable platinum or palladium compounds; however, in some cases it may be advantageous to impregnate thecarrier material when it is in a gelled state.

Yet another essential ingredient of the present catalytic composite isan iridium component. It is of fundamental importance that substantiallyall of the iridium component exists within the catalytic composite ofthe present invention in the elemental state and the subsequentlydescribed reduction procedure is designed to accomplish this objective.The iridium component may be utilized in the composite in any amountwhich is catalytically effective, with the preferred amount being about0.01 to about 2 wt. thereof, calculated on an elemental iridium basis.Typically best results are obtained with about 0.05 to about 1 wt.iridium. It is, additionally, preferred to select the specific amount ofiridium from within this broad weight range as a function of the amountof the platinum or palladium component, on an atomic basis, as isexplained hereinafter.

This iridium component may be incorporated into the catalytic compositein any suitable manner known to those skilled in the catalystformulation art which results in a relatively uniform dispersionofiridium in the carrier material. In addition, it may be added at anystage of the preparation of the composite either during preparation ofthe carrier material or thereafter and the precise method ofincorporation used is not deemed. to be critical. However, best resultsare throught to be obtained when the iridium component is relativelyuniformly distributed throughout the carrier material, and the preferredprocedures are the ones known to result in a composite having thisrelatively lllll uniform distribution. One acceptable procedure forincorporating this component into the composite involves cogelling orcoprecipitating the iridium component during the preparation of thepreferred carrier material, alumina. This procedure usually comprehendsthe addition of a soluble, decomposable compound of iridium such asiridium tetrachloride to the alumina hydrosol before it is gelled. Theresulting mixture is then finished by conventional gelling, aging,drying and calcination steps as explained hereinbefore. A preferred wayof incorporating this component is an impregnation step wherein theporous carrier material is impregnated with a suitableiridium-containing solution either before, during or after the carriermaterial is calcined. Preferred impregnation solutions are aqueoussolutions of water soluble, decomposable iridium compounds such asiridium tribromide, iridium dichloride, iridium tetrachloride, iridiumoxalic acid, iridium sulfate, potassium iridochloride, chloroiridic acidand the like compounds. Best results are ordinarily obtained when theimpregnation solution is an aqueous solution of chloroiridic acid orsodium chloroiridate. This component can be added to the carriermaterial, either prior to, simultaneously with or after the othermetallic components are combined therewith. Best results are usuallyachieved when this component is added simultaneously with the platinumor palladium components.

Yet another essential ingredient of the catalyst used in the presentinvention is the alkali or alkaline earth component. More specifically,this component is selected from the group consisting of the compounds ofthe alkali metals cesium, rubidium, potassium, sodium, and lithium andof the alkaline earth metals calcium, strontium, barium, and magnesium.This component exists within the catalytic composite in an oxidationstate above that of the elemental metal such as a relatively stablecompound such as the oxide or sulfide, or in combination with one ormore of the other components of the composite, or in combination withthe carrier material such as, for example, in the form ofa metalaluminate. Since, as is explained hereinafter, the composite containingthe alkali or alkaline earth is always calcined in an air atmospherebefore use in the conversion of hydrocarbons, the most likely state thiscomponent exists in during use in thedehydrogenation reaction is thecorresponding metallic oxide such as lithium oxide, potassium oxide,sodium oxide and the like. Regardless of what precise form in which itexists in the composite, the amount of this component utilized ispreferably selected to provide a composite containing about 0.1 to about5 wt. of the alkali or alkaline earth metal, and, more preferably, about0.25 to about 3.5 wt. Best results are obtained when this component is acompound of lithium or potassium. The function of this component is toneutralize any of the acidic materials which may have been used in thepreparation of the present catalyst so that the final catalyst isnonacidic.

This alkali or alkaline earth component may be combined with the porouscarrier material in any manner known to those skilled in the art toresult in a relatively uniform dispersion of this component throughoutthe carrier material with consequential neutralization of any acidicsites which may be present therein. Typically good results are obtainedwhen it is combined by impregnation, coprecipitation, ionexchange, andthe like procedures. The preferred procedure, however, involvesimpregnation of the carrier material either before during or after it iscalcined, or before, during or after the other metallic ingredients areadded to the carrier material. Best results are ordinarily obtained whenthis component is added to the carrier material after the other metalliccomponents because the alkali metal or alkaline earth metal acts toneutralize the acid used in the preferred impregnation procedure forthese metallic components. In fact, it is preferred to add the platinumor palladium, iridium and Group IVA metallic components to the carriermaterial, oxidize the resulting composite in an air stream at a hightemperature (i.e., typically about 600 to 1000F.), then treat theresulting oxidized composite with a mixture of air and steam in order toremove at least a portion of any residual acidity and thereafter add thealkali metal or alkaline earth component. Typically, the impregnation ofthe carrier material with this component is performed by contacting thecarrier material with a solution of a suitable decomposable compound orsalt of the desired alkali or alkaline earth metal. Hence, suitablecompounds include the alkali metal or alkaline earth metal halides,sulfates, nitrates, acetates, carbonates, phosphates and the likecompounds. For example, excellent resultsare obtained by impregnatingthe carrier material after the platinum or palladium, iridium and GrouplVA metallic components have been combined therewith, with an aqueoussolution of lithium nitrate or potassium nitrate.

Regarding the preferred amounts of the various metallic components ofthe subject catalyst, l have found it to be a good practice to specifythe amounts of the iridium component, the Group lVA metallic componentand the alkali or alkaline earth component, as a function of the amountof the platinum or palladium component. On this basis, the amount of theiridium component is ordinarily selected so that the atomic ratio ofiridium to platinum or palladium metal is about 0. l :1 to about 2:1,with the preferred range being about 0.25:1 to 1.521. Similarly, theamount of the Group IVA metallic component is ordinarily selected toproduce a composite having an atomic ratio ofGroup IVA metal to platinumor palladium metal within the broad range of about 0.05:1 to :1.However, for the Group lVA metal to platinum group metal ratio, the bestpractice is to select this ratio on the basis of the following preferredrange for the individual species: (1) for germanium, it is about 0.3:]to 10:1, with the most preferred range being about 0.6:1 to about 6: 1;(2) for tin, it is about 0.121 to 3:1, with the most preferred rangebeing about 0.521 to :1; and (3) for lead, it is about 0.05:1 to 0.9:1,with the most preferred range being about 0.121 to 0.75:1. Similarly,the amount of the alkali or alkaline earth component is ordinarilyselected to produce a composite having an atomic ratio of alkali oralkaline earth metal to platinum or palladium metal of about 5:1 toabout 50:1 or more, with the preferred range being about 10:1 to about25:1.

Another significant parameter fot the instant catalyst is the totalmetals content" which is defined to be the sum of the platinum orpalladium component, the iridium component. the Group lV-A metalliccomponent, and the alkali or alkaline earth component, calculated on anelemental metal basis. Good results are ordinarily obtained with thesubject catalyst when this parameter is fixed at a value of about 0.2 toabout 5 wt.%, with best results ordinarily achieved at a metals loadingof about 0.4 to about 4 wt.%.

Integrating the above discussion ofeach of the essential components ofthe catalytic composite used in the present invention, it is evidentthat a particularly preferred catalytic composite comprises acombination of a platinum component, an iridium component, a Group lV-Ametallic component and an alkali or alkaline earth component with analumina carrier material in amounts sufficient to result in thecomposite containing from about 0.05 to about 1 wt.% platinum, about 1wt.% iridium, about 0.05 to about 2 wt.% of the Group lV-A metal andabout 0.25 to about 3.5 wt.% of the alkali or alkaline earth metal.

Regardless of the details of how the components of the catalyst arecombined with the porous carrier material, the resulting multimetalliccomposite generally will be dried at a temperature of about 200F. toabout 600F. for a period of from about 2 to 24 hours or more, andfinally calcined at a temperature of about 600F. to about 1 F. in an airatmosphere fora period of about 0.5 to 10 hours, preferably about 1 toabout 5 hours, in order to convert substantially all the metalliccomponents to the corresponding oxide form. When acidic components arepresent in any of the reagents used to effect incorporation of any oneof the components ofthe subject composite, it is a good practice tosubject the resulting composite to a high temperature treatment withsteam or with a mixture of steam and air, either after or before thecalcination step described above, in order to remove as much as possibleof the undesired acidic component. For example, when the platinum orpalladium component is incorporated by impregnating the carrier materialwith chloroplatinic acid, it is preferred to subject the resultingcomposite to a high temperature with steam in order to remove as much aspossible of the undesired chloride.

It is essential that the resultant multimetallic calcined catalyticcomposite be subjected to a substantially water-free reduction prior toits use in the conversion of hydrocarbons. This step is designed toinsure a uniform and finely divided dispersion of the metalliccomponents throughout the carrier material. Preferably. substantiallypure and dry hydrogen (i.e., less than 20 vol. ppm. H O) is used as thereducing agent in this step. The reducing agent is contacted with thecalcined composite at a temperature of about 800F. to about 1200F., agas hourly space velocity of about 100 to about 5,000 hr. and for aperiod of time of about 0.5 to 10 hours or more, effective to reduce atleast substantially all the platinum or palladium and iridium componentsto the corresponding elemental metallic state while maintaining theGroup lVA component in a positive oxidation state. This reductiontreatment may be performed in situ as part ofa start-up sequence ifprecautions are taken to predry the plant to a substantially water-freestate and if substantially water-free hydrogen is used.

The resulting reduced multimetallic catalytic composite may, in somecases, be beneficially subjected to a presulfiding operation designed toincorporate in the catalytic composite from about 0.05 to about 0.5 wt.sulfur calculated on an elemental basis. Preferably, this presulfidingtreatment takes place in the presence of hydrogen and a suitablesulfur-containing compound such as hydrogen sulfide, lower molecularweight mercaptans, organic sulfides, etc. Typically. this procedurecomprises treating the reduced catalyst with a sulfiding gas such as amixture containing a mole ratio of H to H 8 of about 10:1 at conditionssufficient to effect the desired incorporation of sulfur, generallyincluding a temperature ranging from about 50F. up to about ll00F. ormore. This presulfiding step can be performed in situ or ex situ.

According to the method of the present invention, the dehydrogenatablehydrocarbon is contacted with the instant multimetallic catalyticcomposite in a dehydrogenation zone at dehydrogenation conditions. Thiscontacting may be accomplished by using the catalyst in a fixed bedsystem, a moving bed system, a fluidized bed system, or in a batch typeoperation; however, in view of the danger of attrition losses of thevaluable catalyst and of well-known operation advantages, it ispreferred to use a fixed bed system. In this system, the hydrocarbonfeed stream is preheated by any suitable heating means to the desiredreaction temperature and then passed into a dehydrogenation zonecontaining a fixed bed of the catalyst type previously characterized. Itis, of course, understood that the dehydrogenation zone may be one ormore separate reactors with suitable heating means therebetween toinsure that the desired conversion temperature is maintained at theentrance to each reactor. It is also to be noted that the reactants maybe contacted with the catalyst bed in either upward, downward, or radialflow fashion, with the latter being preferred. In addition, it is to benoted that the reactants may be in the liquid phase, a mixed liqidvaporphase, or a vapor phase when they contact the catalyst, with bestresults-obtained in the vapor phase.

Although hydrogen is the preferred diluent for use in the subjectdehydrogenation method, in some cases other art-recognized diluents maybe advantageously utilized such as steam, methane, carbon dioxide, andthe like diluents. Hydrogen is preferred because it serves thedual-function of not only lowering the partial pressure of thedehydrogenatable hydrocarbon, but also of suppressing the formation ofhydrogendeficient, carbonaceous deposits on the catalytic composite.Ordinarily, hydrogen is utilized in amounts sufficient to insure ahydrogen to hydrocarbon mole ratio of about 1:1 [to about with bestresults obtained in the range of about 1.511 to about 10: l The hydrogensteam charged to the dehydrogenation zone will typically be recyclehydrogen obtained from the effluent stream from this zone after asuitable separation step.

When hydrogen is used as the diluent, a preferred practice is to addwater or a water-producing compound to the dehydrogenation zone. Thiswater additive may be included in the charge stock, or in the hydrogenstream, or in both of these, or added independently of, these.Ordinarily, it is preferred to inject the necessary water by saturatingat least a portion of the input hydrogen stream with water. Good resultsare also obtained when a water-producing compound such as a C to Calcohol is added to the charge stock. Regardless of the source of thewater, the amount of equivalent water added should be sufficient tomaintain the total amount of water continuously entering thedehydrogenation zone in the range of about to about [0.000 wt. ppm. ofthe charge stock, with best results obtained at a level corresponding toabout 1500 to 5000 wt. ppm. of the charge stock.

Concerning the conditions utilized in the process of the presentinvention, these are generally selected from the conditions well knownto those skilled in the art for the particular dehydrogenatablehydrocarbon which is charged to the process. More specifically, suitablecon version temperatures are selected from the range of about 700 toabout 1200F., with a value being selected from the lower portion of thisrange for the more easily dehydrogenated hydrocarbons such as the longchain normal paraffins and from the higher portion of this range for themore difficultly dehydrogenated hydrocarbons such as propane, butane,and the like hydrocarbons. For example, for the dehydrogenation of C toC normal paraffins, best results are ordinarily obtained at atemperature of about 800 to about 950F. The pressure utilized isordinarily selected at a value which is as low as possible consistentwith the maintenance of catalyst stability, and is usually about 0.1 toabout l0 atmospheres, with best results ordinarily obtained in the rangeof about 0.5 to about 3 atmospheres. In addition, a liquid hourly spacevelocity (calculated on the basis ofthe volume amount, as a liquid, ofhydrocarbon charged to the dehydrogenation zone per hour divided by thevolume of the catalyst bed utilized) is selected from the range of aboutI to about 40hr. with best results for the dehydrogenation of long chainnormal paraffins typically obtained at a relatively high space velocityof about 25 to 35 hr.

Regardless of the details concerning the operation of thedehydrogenation step, an effluent stream will be withdrawn therefrom.This effluent will contain unconverted dehydrogenatable hydrocarbons,hydrogen, and products of the dehydrogenation reaction. This stream istypically cooled and passed to a separating zone wherein a hydrogen-richvapor phase is allowed to separate from a hydrocarbon-rich liquid phase.In general, it is usually desired to recover the unreacteddehydrogenatable hydrocarbon from this hydrocarbon-rich liquid phase inorder to make the dehydrogenation process economically attractive. Thisrecovery step can be accomplished in any suitable manner known to theart such as by passing the hydro-carbon-rich liquid phase through a bedof suitable adsorbent material which has the capability to selectivelyretain the dehydrogenated hydrocarbons contained therein or bycontacting same with a solvent having a high selectivity for thedehydrogenated hydrocarbon or by a suitable fractionation scheme wherefeasible. In the case where the dehydrogenated hydrocarbon is a monoolefin, suitable adsorbents having this capability are activated silicagel, activated carbon, activated alumina, various types of speciallyprepared molecular sieves, and the like adsorbents. In another typicalcase, the dehydrogenated hydrocarbons can be separated from theuncoverted dehydrogenatable hydrocarbons by utilizing the inherentcapability of the dehydrogenated hydrocarbons to enter into severalwell-known chemical reactions such as alkylation, oligomerization,halogenation, sulfonation, hydration, oxidation, and the like reactions.Irrespective of how the dehydrogenated hydrocarbons are separated fromthe unreacted hydrocarbons, a stream containing the unreacteddehydrogenatable hydrocarbons will typically be recovered from thishydrocarbon separation step and recycled to the dehydrogenation step.Likewise. the hydrogen phase present in the hydrogen separating zonewill be withdrawn therefrom, a portion of it vented from the system inorder to remove the net hydrogen make, and the remaining portion istypically recycled, through suitable compressing means, to thedehydrogenation step in order to provide diluent hydrogen therefor.

In a preferred embodiment of the present invention wherein long chainnormal paraffin hydrocarbons are dehydrogenated to the correspondingnormal monoolefins, a preferred mode of operation of this hydrocarbonseparation step involves an alkylation reaction. In this mode, thehydrocarbon-rich liquid phase withdrawn from the separating zone iscombined with a stream containing an alkylatable aromatic and theresulting mixture passed to an alkylation zone containing a suitablehighly acidic catalyst such as an anhydrous solution of hydrogenfluoride. In the alkylation zone the mono-olefins react with thealkylatable aromatic while the unconverted normal paraffins remainsubstantially unchanged. The effluent stream from the alkylation zonecan then be easily separated, typically by means of a suitablefractionation system, to allow recovery of the unreacted normalparaffins. The resulting stream of unconverted normal paraffins is thenusually recycled to the dehydrogenation step of the present invention.

The following working examples are introduced to illustrate further thenovelty, mode of operation, utility and benefits associated with thedehydrogenation method and multimetallic catalytic composite of thepresent invention. These examples are intended to be illustrative ratherthan restrictive.

These examples are all performed in a laboratory scale dehydrogenationplant comprising a reactor, a hydrogen separating zone, a heating means,cooling means, pumping means, compressing means, and the like equipment.In this plant the feed stream containing the dehydrogenatablehydrocarbon is combined with a hydrogen stream and the resultant mixtureheated to the desired conversion temperature, which refers herein to thetemperature maintained at the inlet to the reactor. The heated mixtureis then passed into contact with the catalyst which is maintained as afixed bed of catalyst particles in the reactor. The pressures reportedherein are recorded at the outlet from the reactor. An effluent streamis withdrawn from the reactor, cooled, and passed into the separatingzone wherein a hydrogen gas phase separates from a hydrocarbon-richliquid phase containing dehydrogenated hydrocarbons, uncoverteddehydrogenatable hydrocarbons and a minor amount of side products of thedehydrogenation reaction. A portion of the hydrogen-rich gas phase isrecovered as excess recycle gas with the remaining portion beingcontinuously recycled through suitable compressive means to the heatingzone as described above. The hydrocarbon-rich liquid phase from theseparating zone is withdrawn therefrom and subjected to analysis todetermine conversion and selectivity for the desired dehydrogenatedhydrocarbon as will be indicated in the examples. Conversion numbers ofthe dehydrogenatable hydrocarbon reported herein are all calculated onthe basis of disappearance of dehydrogenatable hydrocarbon and areexpressed in mole percent. Similarly, selectivity numbers are reportedon the basis of moles of desired hydrocarbon produced per 100 moles ofdehydrogenatable hydrocarbon converted.

All of the catalysts utilized in these examples are prepared accordingto the following general method with suitable modifications instoichiometry to achieve the compositions reported in each example.First, an alumina carrier material comprising one-sixteenth inch spheresis prepared by: forming an aluminum hydroxyl chloride sol by dissolvingsubstantially pure aluminum pellets in a hydrochloric acid solution,adding hexamethylenetetramine to the sol, gelling the resulting solutionby dropping it into an oil bath to form spherical particles of analumina hydrogel, aging, and washing the resulting particles with anammoniacal solution and finally drying, calcining, and steaming the agedand washed particles to form spherical particles of gammaaluminacontaining substantially less than (H wt. "/1 combined chloride.Additional details as to this method of preparing this alumina carriermaterial are given in the teachings of US. Pat. No. 2,6203 I4.

Second, a measured amount of germanium tetrachloride is dissolved inanhydrous ethanol. The resulting solution is aged at room temperatureuntil an equilibrium condition is established therein. An aqueoussolution containing chloroplatinic acid, choroiridic acid and nitricacid is also prepared. The two solutions are then intimately admixed andused to impregnate the gammaalumina particles. The amounts of thevarious reagents are carefully selected to yield final catalyticcomposites containing the required amounts of platinum, iridium andgermanium. In order to insure uniform distribution of metalliccomponents throughout the carrier material, this impregnation step isperformed by adding the alumina particles to the impregnation mixturewith constant agitation. The impregnation mixture is maintained incontact with the alumina particles for a period of about one-half hourat a temperature of F. thereafter, the temperature of the impregnationmixture is raised to about 225F. and the excess solution is evaporatedin a period of about 1 hour. The resulting dried particles are thensubjected to a calcination treatment in an air atmosphere at atemperature of about 500 to about 1000F. for about 2 to 10 hourseffective to convert the metallic components to the correspondingoxides. Thereafter, the resulting calcined particles are treated with anair stream containing from about 10 to about 30% steam at a temperatureof about 800 to about 1000F. for an additional period from about 1 toabout 5 hours in order to further reduce the residual combined chloridein the composite.

Finally, the alkali or alkaline earth metal component is added to theresulting calcined particles in a second impregnating step. This secondimpregnation step involves contacting the calcined particles with anaqueous solution of a suitable decomposable salt of the desired alkalior alkaline earth component. For the composites utilized in the presentexamples, the salt is either lithium nitrate or potassium nitrate. Theamount of this salt is carefully chosen to result in a final compositehaving the desired composition. The resulting alkali impregnatedparticles are then dried, calcined and steamed in exactly the samemanner as described above following the first impregnation step.

In all the examples the catalyst is reduced during start-up contactingwith hydrogen at an elevated temperature of about 900 to l F. for aperiod of time sufficient to reduce substantially all of the platinumand iridium components to the elemental state while maintaining theother components in a positive oxidation state. Thereafter, thecomposite is sulfided with a mixture of H and H S as explainedhereinbefore.

EXAMPLE I The reactor is loaded with 100 cc's ofa catalyst containing,on an elemental basis, 0.375 lwt. platinum,

0.375 wt. iridium, 0.25 wt. germanium, 0.5 wt. lithium and less than0.15 wt. chloride. The feed stream utilized is commercial gradeisobutane containing 99.7 wt. isobutane and 0.3 wt. normal butane. Thefeed stream is contacted with the catalyst at a temperature of 1065F., apressure of psig., a liquid hourly space velocity of4.0 hr. and ahydrogen to hydrocarbon mole ratio of 2:1. The dehydrogenation plant islined-out at these conditions and a 20 hour test period commenced. Thehydrocarbon product stream from the plant is continuously analyzed byGLC (gasliquid chromotography) and a high conversion of isobutane isobserved with good selectivity for isobutylene.

EXAMPLE II The catalyst contains, on an elemental basis, 0.25 wt. 72platinum, 0.5 wt. germanium, 0.25 wt. iridium, 0.5 wt. lithium, and lessthan 0.15 wt. combined chloride. The feed stream is commercial gradenormal dodecane. The dehydrogenation reactor is operated at atemperature of 870F., a pressure of 10 psig., a liquid hourly spacevelocity of 32 hr. and a hydrogen to hydrocarbon mole ratio of 8:1.After a line-out period, a 20 hour test period is performed during whichthe average conversion of the normal dodecane is maintained at a highlevel with a selectivity for dodecene of above 90%.

EXAMPLE Ill The catalyst is the same as utilized in Example 11. The feedstream is normal tetradecane. The conditions utilized are a temperatureof 840F., a pressure of 20 psig., a liquid hourly space velocity of 32hr., and a hydrogen to hydrocarbon mole ratio of 8:1. After a line-outperiod. a 20 hour test shows an average conversion of approximately 12%and a selectivity for tetradecene of above about 90%.

EXAMPLE IV The catalyst contains, on an elemental basis, 0.2 wt.platinum, 0.2 wt. iridium, 0.25 wt. germanium and 0.6 wt. lithium, withcombined chloride being less than 0.2 wt. The feed stream issubstantially pure normal butane. The conditions utilized are atemperature of 950F., a pressure of 15 psig., a liquid hourly spacevelocity of4.0 hr. and a hydrogen to hydrocarbon mole ratio of 4:1.After a line-out period, a hour test is performed and excellentconversion of the normal butane to butene is observed.

EXAMPLE V The catalyst contains, on an elemental basis, 0.375 wt.platinum 0.375 wt. iridium, 0.5 wt. germanium, 2.8 wt. potassium, andless than 0.2 wt. combined chloride. The feed stream is commercial gradeethylbenzene. The conditions utilized are a pressure of 15 psig., aliquid hourly space velocity of 32 hrf, a temperature of 950F., and ahydrogen to hydrocarbon mole ratio of 8:1. During a 20 hour test period,at least 85% of equilibrium conversion of ethylbenzene is observed withhigh selectivity for styrene.

lt is intended to cover by-the following claims all changes andmodifications of the above disclosure of the present invention thatwould be self-evident to a man of ordinary skill in the catalystformulation art or in the hydrocarbon dehydrogenation art.

I claim as my invention:

11. A method for dehydrogenating a dehydrogenatable hydrocarboncomprising contacting the hydrocarbon with a nonacidic catalyticcomposite comprising a pourous carrier material containing, on anelemental basis, about 0.01 to about 2 wt. platinum or palladium, about0.01 to 2 wt.% iridium, about 0.01 to about 5 wt. germanium and about0.1 to about 5 wt.% of an alkali or alkaline earth metal, wherein theplatinum or palladium, iridium, germanium and alkali or alkaline earthmetal components are uniformly dispersed throughout the porous carriermaterial, wherein substantially all of the platinum or palladium andiridium components are present in the corresponding elemental metallicstate, wherein substantially all of the germanium component is presentin an oxidation state above that of the elemental metal and whereinsubstantially all of the alkali or alkaline earth metal component ispresent in an oxidation state above that of the ele mental metal atdehydrogenation conditions.

2. A method as defined in claim 1 wherein the porous carrier material isa refractory inorganic oxide.

3. The method as defined in claim 2 wherein the re fractory inorganicoxide is alumina.

4. A method as defined in claim 1 wherein the alkali or alkaline earthmetal is lithium.

5. A method as defined in claim 1 wherein the alkali or alkaline earthmetal is potassium.

6. A method as defined in claim 1 wherein the atomic ratio of germaniumto platinum or palladium is about 0.05:1 to about 10:1, wherein theatomic ratio of iridium to platinum or palladium is about 0.121 to about2:1 and wherein the atomic ratio of the alkali or alkaline earth metalto platinum group metal is about 5:1 to 50:1.

7. A catalytic method as defined in claim 1 wherein the compositecontains about 0.05 to about 0.5 wt. 76 sulfur, calculated on anelemental basis.

8. A method as defined in claim 1 wherein substantially all of thegermanium is present as germanium oxide.

9..A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is admixed with hydrogen when it contacts the catalyticcomposite.

10. A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is an aliphatic compound containing 2 to 30 carbon atoms permolecule.

111. A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is a normal paraffin hydrocarbon containing about'4 to 30carbon atoms per molecule.

12. A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is a normal paraffin hydrocarbon containing about 10 toabout 18 carbon atoms per molecule.

13. A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is an alkylaromatic, the alkyl groupwhich contains 2 to 6carbon atoms.

14'. A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is a naphthene.

115. A method as defined in claim 1 wherein said dehydrogenationconditions include a temperature of about 700 to about 1200F., apressure of about 0.1 to about 10 atmospheres, a liquid hourly spacevelocity of about 1 to 40 hr. and a hydrogen to hydrocarbon mole ratioof about 1:1 to about 20:1.

about 0.05 to about 1 wt.% iridium, about 0.05 to about 2 wt.% germaniumand about 0.25 to about 3.5 wt.% alkali or alkaline earth metal andwherein the porous carrier material is alumina.

1. A METHOD FOR DEHYDROGENATING A DEHYDROGENATABLE HYDROCARBONCOMPRISING CONTACTING THE HYDROCARBON WITH A NONACIDIC CATALYTICCOMPOSITE COMPRISING A POUROUS CARRIER MATERIAL CONTAINING, ON ANEMEMENTAL BASIS, ABOUT 0.01 TO ABOUT 2 WT. % PLATINUM OR PALLADIUM,ABOUT 0.01 TO 2 WT. % IRIDIUM, ABOUT 0.01 TO ABOUT 5WT.% GERMANIUM ANDABOUT 0.1 TO ABOUT 5WT% OF AN ALKALI OR ALKALINE EARTH METL, WEHREIN THELATINUM OR PALLADIUM, IRIDIYUM, GERMANIUM AND ABOUT 0.1 ALKALINE EARTHMETAL COMPONENTS ARE UNIFORMLY DISPERSED THROUGHOUT THE POROUS CARRIERMATERIAL, WHEREIN SUBSTANTIALLY ALL OF THE PLATINUM OR PALLADIUM ANDIRIDIUM COMPONENTS ARE PRESENT IN THE CORRESPONDING ELEMENTAL METALLICSTATE, WHEREIN SUBSTANTIALLY ALL OF THE ALKALI OR ALKALINE EARTH METALCOMPOOXIDATION STATE ABOVE THAT OF THE ELEMENTAL METAL AND WHEREINSUBSTANTIALLY ALL OF THE ALKALI OR ALKALINE EARTH METAL COMPONENT ISPRESENT IN AN OXIDATION STATE ABOVE THAT OF THE ELEMENTAL METAL ATDEHYDROGENATION CONDITIONS.
 2. A method as defined in claim 1 whereinthe porous carrier material is a refractory inorganic oxide.
 3. Themethod as defined in claim 2 wherein the refractory inorganic oxide isalumina.
 4. A method as defined in claim 1 wherein the alkali oralkaline earth metal is lithium.
 5. A method as defined in claim 1wherein the alkali or alkaline earth metal is potassium.
 6. A method asdefined in claim 1 wherein the atomic ratio of germanium to platinum orpalladium is about 0.05:1 to about 10:1, wherein the atomic ratio ofiridium to platinum or palladium is about 0.1:1 to about 2:1 and whereinthe atomic ratio of the alkali or alkaline earth metal to platinum groupmetal is about 5:1 to 50:1.
 7. A catalytic method as defined in claim 1wherein the composite contains about 0.05 to about 0.5 wt. % sulfur,calculated on an elemental basis.
 8. A method as defined in claim 1wherein substantially all of the germanium is present as germaniumoxide.
 9. A method as defined in claim 1 wherein said dehydrogenatablehydrocarbon is admixed with hydrogen when it contacts the catalyticcomposite.
 10. A method as defined in claim 1 wherein saiddehydrogenatable hydrocarbon is an aliphatic compound containing 2 to 30carbon atoms per molecule.
 11. A method as defined in claim 1 whereinsaid dehydrogenatable hydrocarbon is a normal paraffin hydrocarboncontaining about 4 to 30 carbon atoms per molecule.
 12. A method asdefined in claim 1 wherein said dehydrogenatable hydrocarbon is a normalparaffin hydrocarbon containing about 10 to about 18 carbon atoms permolecule.
 13. A method as defined in claim 1 wherein saiddehydrogenatable hydrocarbon is an alkylaromatic, the alkyl group whichcontains 2 to 6 carbon atoms.
 14. A method as defined in claim 1 whereinsaid dehydrogenatable hydrocarbon is a naphthene.
 15. A method asdefined in claim 1 wherein said dehydrogenation conditions include atemperature of about 700* to about 1200*F., a pressure of about 0.1 toabout 10 atmospheres, a liquid hourly space velocity of about 1 to 40hr. 1 and a hydrogen to hydrocarbon mole ratio of about 1:1 to about20:1.
 16. A method for dehydrogenating a dehydrogenatable hydrocarboncomprising contacting the hydrocarbon with the catalytic composite asdefined in claim 1 wherein the composite contains, on an elementalbasis, about 0.05 12C357666en to about 1 wt. % platinum or palladium,about 0.05 to about 1 wt. % iridium, about 0.05 to about 2 wt.%germanium and about 0.25 to about 3.5 wt.% alkali or alkaline earthmetal and wherein the porous carrier material is alumina.